The present invention relates to a heat exchanger having a simple structure and being easily produced, which can be used as a heat exchanger (EGR cooler) used in an exhaust gas recirculation apparatus of an automobile or another heat exchanger.
A conventional EGR cooler comprises an assembly of a large number of flat tubes or plates, a large number of fins, a casing, and a header, wherein cooling water is made to flow on the side of the casing and an exhaust gas is made to flow in the interior of the flat tubes or the like as the invention disclosed in Japanese Unexamined Patent Publication No. 2003-90693 for example.
The drawbacks of such a heat exchanger as an EGR cooler or the like have been that: the number of parts is large, which makes assembling cumbersome; and the number of brazed portions of each component increases, which causes leakage to tend to occur at the brazed portions. Moreover, it has been feared that the portions where a fluid stagnates may be caused in a flow channel and cooling water may partially come to a boil.
In order to prevent those drawbacks from occurring, in the invention disclosed in the aforementioned Japanese patent publication: a pair of blocking projecting stripes is intermittently provided particularly on the outer surface of a tube at the downstream position of an inlet for cooling water; the cooling water is injected from an inlet pipe and collided with the casing facing the inlet pipe; the reflecting streams are introduced to the projecting stripes and then introduced to an intermediate portion where no stripes exist. The drawbacks thereof have been that the production of such a tube is cumbersome and the cooling water does not flow evenly in each part on a tube surface.
In view of the above situation, an object of the present invention is to provide a heat exchanger that: has a small number of parts; is easy to assemble; has a small number of brazed portions; is highly reliable; can flow cooling water evenly to each part; and does not cause partial boiling.